Hi,
I am not sure if the following is what you asked, however this is what I find in tables.sql for the image table:
CREATE TABLE /*_*/image (
-- Filename.
-- This is also the title of the associated description page,
-- which will be in namespace 6 (NS_FILE).
img_name varchar(255) binary NOT NULL default '' PRIMARY KEY,
-- File size in bytes.
img_size int unsigned NOT NULL default 0,
-- For images, size in pixels.
img_width int NOT NULL default 0,
img_height int NOT NULL default 0,
-- Extracted Exif metadata stored as a serialized PHP array.
img_metadata mediumblob NOT NULL,
-- For images, bits per pixel if known.
img_bits int NOT NULL default 0,
-- Media type as defined by the MEDIATYPE_xxx constants
img_media_type ENUM("UNKNOWN", "BITMAP", "DRAWING", "AUDIO", "VIDEO", "MULTIMEDIA", "OFFICE", "TEXT", "EXECUTABLE", "ARCHIVE") default NULL,
-- major part of a MIME media type as defined by IANA
-- see http://www.iana.org/assignments/media-types/
-- for "chemical" cf. http://dx.doi.org/10.1021/ci9803233 by the ACS
img_major_mime ENUM("unknown", "application", "audio", "image", "text", "video", "message", "model", "multipart", "chemical") NOT NULL default "unknown",
-- minor part of a MIME media type as defined by IANA
-- the minor parts are not required to adher to any standard
-- but should be consistent throughout the database
-- see http://www.iana.org/assignments/media-types/
img_minor_mime varbinary(100) NOT NULL default "unknown",
-- Description field as entered by the uploader.
-- This is displayed in image upload history and logs.
img_description varbinary(767) NOT NULL,
-- user_id and user_name of uploader.
img_user int unsigned NOT NULL default 0,
img_user_text varchar(255) binary NOT NULL,
-- Time of the upload.
img_timestamp varbinary(14) NOT NULL default '',
-- SHA-1 content hash in base-36
img_sha1 varbinary(32) NOT NULL default ''
) /*$wgDBTableOptions*/;